KB. C. B. CLARKE OX DIMORPHISM IX THE RUBIACEJE. 



159 



On two Kinds of Dimo 



in the Eubiacese 



By Charles Babon Clarke, M.A., F.L.S. 



[Read June 20, 1878.] 



Mr. Darwin has described, under the name dimorphism, the case 

 where one species possesses two kinds of flowers, viz. one with 

 long filaments and a short style, the other with short filaments 

 and a long style. These are reciprocally fertile ; and such dimor- 

 phism forms one of the routes towards dioicism. This kind of 

 dimorphism is found in many natural orders, and is very frequent 

 in the Rubiacea?, as in the type genus Cinchona. 



In this kind of dimorphism the differences between the two 

 forms of flower are of slight systematic importance ; the older 

 authors have used the character of longer or shorter style, 

 longer or shorter filaments, to distinguish species in genera 

 where many (if not all) species possess both kinds of flowers. In 

 the case, however, of the genus Adenosacme the dimorphism is of 

 a different kind, affecting a character of first-rate systematic im- 

 portance, viz. the point of insertion of the stamens. Here the 

 short-styled form has the stamens inserted high on the corolla- 

 tube; the long-styled form has the stamens attached at the very 

 base of the corolla- tube, almost free from it. 



Adenosacme is a genus of small shrubs ; A. longifolia, Wall., is 

 common in Sikkim and Khasia, where I have often examined the 

 fresh flowers. Fig. 1 is a copy of a vertical section of the short- 

 styled form noted on one of my field-tickets ; fig. 2 of the long- 



Fig. 1. 



Fig. 2. 



Diagrammatic representation of vertical sections of the flower of Ademsacmr 

 hngifolia. Fig. 1, short styled, and fig. 2, long-styled variety. Both X 5 



diameter*. 



